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Cooling Fan Installation for RCA 400 Series Interactive Players


This page provides instructions for installing a cooling fan in RCA's SJT400 and SKT400 players. In contrast to other J/K players, these models have an extra circuit board in the form of a sandwich, that provides the additional circuitry needed for the interactive remote functions. The On Screen Display (OSD) integrated circuit on this board is subject to overheating, which usually results in a washed out appearance to the video image after the player has been on for a few minutes to an hour. There are several reasons why this OSD chip has a tendency to overheat.


This heat-related failure seems to be on the rise with 400 series players, so I've been investigating ways to overcome it. There are several methods to dissipate heat from the OSD chip, but the installation of a small fan inside the sandwich directly between the U6103 and U6101 chips seems to be the best approach in terms of simplicity and effectiveness. But all the various approaches to fixing this heat failure problem are discussed below.

Placing the J/K Player into the Service Position

CAUTION: This procedure requires working on the exposed electronics of a CED player. Be familiar with, and adhere to these guidelines before proceeding:

The first step in installing a cooling fan is to place the player in the service position, a procedure that is basically the same for all J/K players. These instructions and Black & White photographs come from the RCA service literature.

J/K Chassis Screw Removal

(1) If cabinet top has been removed, remove receiver spindle assembly. Also remove stylus cartridge and store in safe place. Place instrument, bottom up, on workbench with soft surface.

(2) Remove adjusting nut (1/2" hex head) and reinforcing plate (1-1/4" washer) from center of bottom cover (see upper left photo).

(3) Remove five (5) pozi-drive screws (see upper left photo).

(4) Lift off bottom plate and set aside.

(5) Remove thirteen (13) pozi-drive screws (see upper right photo).

(6) Remove main circuit board and PW6100 by lifting front edge up to approximately a 10 to 15 degree angle, so as to clear all obstacles, then move board forward towards front of instrument until antenna connectors clear rear edge of base plate.

(7) After circuit boards are clear of base plate, rotate boards horizontally 90 degrees and lay beside instrument.

(8) Turn bottom plate over and fasten in position on base plate with adjusting nut and reinforcing plate removed in step (2) above.

NOTE: Bottom plate must be installed in prescribed manner to operate instrument in service position.

(9) Place instrument and circuit board in upright position, reinstall receiver spindle assembly and if front panel was removed reconnect front panel flex cable to flex cable connector. Instrument is now in operational service position (see photo below).

(10) To reassemble - reverse procedure.

CAUTION: Replace circuit board mounting screws only in holes from which they were removed (see upper right photo).

J/K Service Position


Installation of the Cooling Fan

The diagram below is a partial schematic of the two halves of the PW6100 board showing the position of the cooling fan and the test points that can be tapped to power the fan. The outline red square is a scale representation of where the fan rests on the lower portion of the PW6100 board. When the two halves of this board are brought back together the U6103 IC is nearly directly above the fan. Note that this fan must measure 1.6" x 1.6" x 0.4" to fit inside the PW6100 sandwich. The three small solid red squares on the diagram indicate from left to right the GND, +12V, and +5V test points. These are metal stakes on the circuit board to which the fan leads can be soldered. The black lead always goes to the Ground TP6102 on the left, while the red lead goes to either the 12 Volt TP6103 or the 5 Volt TP6101, depending on the voltage of the fan being used.
PW6100 Schematic



Fan With Heat Sink Assembled CPU Cooling Fan

I obtained the required fan at a local computer store in the form of a CPU cooling fan intended for installation on the microprocessor in a desktop computer. This was actually cheaper than buying the fan alone from a mail order supplier like Jameco. If you buy the fan locally, take a ruler along to make sure the fan measures 1.6 x 1.6 x 0.4 inches.



Fan With Removed Heat Sink Disassembled CPU Cooling Fan

Here is the fan separated from the heat sink and fastener on the left and the power supply tap above, none of which are required for the CED player installation. Note that the fan is a 12 Volt unit if the red lead from the fan goes to the yellow lead on the computer power supply tap. If it goes to the red lead on the computer power supply tap, the fan is a 5 Volt unit. The voltage will usually be printed on the fan as well.



Separating the PW6100 Separating the PW6100 Sandwich

RCA's service position instructions don't mention how to separate the two halves of the PW6100, so this photo shows the start of the procedure. There are four locking spacers holding the two halves of the board together. Grasp the right most spacer with a small pliers and squeeze the jaws shut. At the same time lift the board up to just clear the jaws. Proceed to the next spacer until all four have been loosened and the boards are separated.



Fan In Place On PW6100 Board Fan In Place on PW6100 Board

In this picture the fan has been installed on the lower portion of the circuit board. It rests on top of the U6101 Features Microcomputer IC and against the bus bar immediately above the fan. When the boards are closed, the U6103 OSD IC (visible at the very top of the picture) is positioned just over the top of the fan. Note that the fan is installed with the exposed center hub facing up. The exposed hub must be facing up to prevent it from rubbing against the board as the fan spins. In this position the fan sucks air around U6103 and blows it down around U6101.
The fan leads can be seen soldered to GND (TP2) and +12V (TP3) as this is a 12 Volt fan. Be careful not to solder the black ground lead to TP10 which is just to the left of the TP2 ground test point.
Note the routing of the thick gray cable going just under the lower left corner of the fan. When the two board halves are brought together this cable is used to loosely secure the fan against the metal bus bar above the fan.



Fan Inside PW6100 Sandwich Fan Installed Inside the PW6100

This final photo shows the fan inside the closed halves of the PW6100 board. Note that the gray cable has been moved to the middle of the fan's side to hold the fan in place. Observe the group of three ribs on the edge of circuit board just above the fan which are an artifact left over from the manufacturing process. A small brown capacitor can be seen just below the left most of the three ribs. This is C6131 (labeled C31 on the board) and it should be bent flat against the board to prevent interference with the fan.
Power the player up while in the service position to verify proper operation of the fan prior to reassembling the player.


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